The parents may look after the fry, don't count on it, they usually do eat them the first couple of times, but they will get the hang of it.
Your other fish will try to eat the fry if they get the chance, often tho the parents won't let others near.
not sure of the exact time frame till they hatch but expect to wait a couple of days at least.
if you can slide a divider into the tank and seperate the angels from the rest of this fish in the tank, this will give them a better chance at raising the young.
Also do not fret if you can't find the young once they hatch as some parents will move the young around the tank.
All The best with the first spawn.
Ballistic